1. Field of the Invention
The present invention is directed to a system for using camera attitude sensors.
2. Description of the Related Art
The remarkable, often astonishing, physical skills and feats of great athletes draw millions of people every day to follow sports. In particular, the number of people watching sports on television and the amount of advertising revenue received for televised sports has increased significantly. To satisfy the increased demand for televised sports, broadcasters have deployed a varied repertoire of technologies to highlight these exciting events for viewers. For example, broadcasters have started adding graphical enhancements to the video of the sporting events. Examples of graphic enhancements have included highlighting moving objects, highlighting portions of a playing field (e.g. first down line), adding virtual advertisements and the addition of other graphics to the video of the event.
The systems being employed for providing graphical enhancements to video have generally fallen into two categories. The first category of systems uses pattern recognition to recognize certain features in the video in order to accurately place the graphic into the video. A second category of systems uses sensors to measure the attitude of the camera capturing the video and then uses the measured camera attitude information to accurately insert the graphic into the video. It has been found that prior systems that only use pattern recognition have not been robust enough to account for rapid movement of the camera during the event and may be too slow for live events. Some systems that use pattern recognition have attempted to compensate for these deficiencies by using camera attitude sensors in combination with pattern recognition.
Systems that rely on camera attitude information require precise measurements of the orientation of a camera at any given time. Certain situations beyond the broadcaster's control can interfere with and be a source of error when measuring camera attitude information. For example, cameras at a sporting event typically are located at predesignated camera locations. Sometimes the camera location has a floor that can sag or wobble. As a heavy camera is panned and tilted, the weight distribution of the camera and/or operator may cause the floor to sag or wobble. A camera operator moving at the camera location may also cause the floor to sag or wobble. Additionally, during an event, the tripod holding the camera can be kicked or moved. The floor of the camera location can also vibrate at either a high frequency or low frequency because of other activity in the stadium, for example, fans jumping, fans stomping their feet, etc. Additionally, mechanical compliance of the various parts of the tripod and mount can also hinder an accurate camera attitude reading.
Thus, there is a need for an improved camera attitude measurement system to better measure camera attitude in light of the sources of error described above.